Review: Tohatsu BFT250A outboard motor

The Tohatsu BFT250A is the easiest to maintain naturally aspirated four-stroke 250 hp outboard on the market.

The Tohatsu BFT250A outboard motor is another "Hondatsu". Of the 250 hp naturally aspirated four-stroke outboard engines, this one is the easiest to maintain.

Tohatsu now has an outboard engine to compete with all the manufacturers. Yep, it’s another Hondatsu, but it represents all of Honda’s engineering expertise in making four-stroke engines that are torquey and fuel efficient but reasonably straightforward to service.

Sure, the Tohatsu BFT250A outboard motor doesn’t have the blistering holeshot of DFI two-stroke engines like the Mercury OptiMax 250 Pro XS but revved out to wide open throttle it stays quiet. My tinnitus gets a break with big four-stroke engines as the crickets constantly chirping in my ears aren’t encouraged to reach a deafening crescendo.

TOHATSU BFT250A

Like all Hondatsu outboards the Tohatsu BFT250A outboard motor has BLAST or Boosted Low Speed Torque that increases fuel flow with a 12:1 ratio to improve holeshot, but as the engine has a fairly long piston stroke I recommend limiting maximum cruising to 5000rpm. Above this rpm the engine uses way more fuel despite having VTEC or variable valve timing that holds the intake valves open longer from 4500rpm to WOT.

In any case midrange running is made sweeter by the ECOmo lean-burn system where the air/fuel ratio is 18:1, reverting to the normal 14.7:1 when the engine is worked hard.

The narrow-fronted and broad backend cowl is designed to induct intake air without water and also rids the powerhead quickly of heat. The design looks deceptively narrow from the cockpit.

The engineering of the Tohatsu BFT250A engine is typical of V6 automotive SUV design with 24 valves; although with only one camshaft per cylinder bank driven by a toothed rubber belt which needs to be replaced about every 1000 hours.

Steel cylinder liners are used for longevity and valve clearance adjustment is made easier using a feeler gauge and 10mm spanner. The belt-driven 60amp voltage regulated alternator is easier to service than an under-flywheel unit.

The Tohatsu BFT250A outboard has a massive 7.8lt engine oil sump to help absorb oil "sludging" during extended trolling periods that afflicts all raw-water cooled four-strokes.

Lakeside Marine, the national Tohatsu distributor, recommends using a semi-synthetic Nulon SAE 10W30 oil in the BFT250A but if this isn’t available, Honda’s own mineral-based FCW (Four Cycle Watercooled) SAE 10W30 oil should do just as good a job.

Maintaining the BFT250A is straightforward with the fuel filter and cannister oil filter easily reached and all wiring neatly routed.

Lakeside recommends servicing intervals of 50 hours or annually after the first 20 hours and if this is performed by an authorised Tohatsu dealer, the recreational warranty is three years.

ON THE WATER

Mounted on a Force F23 social skiboat the review Tohatsu BFT250A outboard was midrange power for this hefty "Cigarette" style hull. It started instantly hot or cold with no oil smoke appearing at any time and trolled with barely a tremor through the hull structure.

Like all well set up performance boats the Force F23 had a foot throttle, jacking plate and hydraulic steering with the remote control box used just for forward and reverse.

As the 25in pitch four-bladed Quicksilver Trophy Plus prop had hub ventilation holes and a smaller hub than the gear case diameter to vent exhaust gases to the blades, from trolling to planing took six seconds. A bit slow for my liking but great for getting two barefoot skiers out of the hole.

A different story once planing though, with only 18 seconds from 3000rpm to WOT, a damned good effort considering the Hondatsu was pushing a total of 1400kg including three adults.

At 3500rpm we found that raising the jacking plate, then trimming the leg out about 60 per cent while hammering the foot throttle gave the best performance to WOT. Through turns we left the plate up, trimmed in the leg then coming out of the turn trimmed it back out again while accelerating hard. Honda has refined its VTEC to the extent that there was no sudden rush of power above 4500rpm and from here to WOT the engine remained quiet with just a background noise of all that mechanical action going on inside it.

THE TRADE-A-BOAT VERDICT

This is the fourth Honda-based 250 I’ve tested since Honda released its own version in November 2011 and it shows how versatile this engine is, whether powering trailerable offshore gameboats or skiboats. Though it’s the heaviest naturally aspirated 250 available the midrange and top-end performance masks this to the extent you’d never know in everyday usage.

The Tohatsu BFT250A has logical design and engineering and is the easiest of the naturally aspirated four-stroke 250hp outboards to maintain and service, with a spare prop costing around $1500. ‘